Heavy rains in southern Alberta have caused flooding, mudslides and the closure of the Trans-Canada Highway around the scenic mountain towns of Banff and Canmore.

Several communities in the mountains and foothills declared states of emergency on Thursday and ordered evacuations as rivers swelled and rising water threatened roads and bridges.

The towns of Canmore and Banff were cut off because of mudslides that closed the Trans-Canada to the east and to the west. The RCMP were warning of several mudslides on highways around Banff and in the popular recreation area of Kananaskis. Several sections or road were reported to be washed out.

"It's a real mess," Sgt. Patricia Neely said. "Not to make light - things are very fluid as to what is going to happen. It will take a little while before these roads are passable."

Parks Canada spokeswoman Michelle Macullo said people caught inside the park didn't really have many options.

"Right now, if people are in Canmore they can get to Banff. People from Banff can get to Canmore," she said. "We just have to wait to see what the weather presents."

Canmore spokeswoman Sally Caudill said motorists were trapped overnight Wednesday by water spilling over the Trans-Canada and had to be rescued by choppers.

"We had about 20 or so people on the highway ... who got stuck,'' she said. "Water covered the highway in two places, so we used a helicopter to get those folks out.''

Caudill said Cougar Creek, which runs through her community, was rising quickly Thursday. The town's website said the creek's banks were unstable and dangerous.

"Cougar Creek is very serious and changing very quickly," Caudill said. "Homes that back immediately onto the creek have been evacuated starting at about 3 this morning. We are now extending that evacuation."

Canmore wasn't the only town with concerns. Similar threats were being felt in High River, Black Diamond and Turner Valley communities along what is know as the Cowboy Trail in the foothills of the Rocky Mountains.

A mandatory evacuation was issued for several areas in High River as the Highwood River rose. The hospital was evacuated and residents of a seniors residence were told to leave.

"It's bad," said High River spokeswoman Joan Botkin. "The most unnerving thing, I guess, is that river forecasters are predicting if we receive another 40 millimetres of rain the Highwood will crest at about 1,270 cubic metres a second between noon and early evening. We encounter flooding at around 210 cubic metres."

Barry Williamson, a councillor in Turner Valley, said that community was in danger of being cut off as well. Traffic was being restricted on the two bridges out of town as water levels crept within a metre of the their decks. The third road out is in a flood-prone area.

Two small subdivisions, home to about 50 people, were being evacuated, he said.

"Go back to 2005, that was our 100-year flood here," Williamson said. "This is looking to be higher than that in terms of the flow of the river and height of the rivers."

Heavy rainfall and lightning overnight Wednesday also resulted in power outages and flashing traffic signals in every area of the city of Calgary. Crews were out Thursday trying to repair the damage. The city declared a local state of emergency and said there was sandbagging in some locations as the Bow and Elbow rivers continued to rise.

Environment Canada issued a rainfall warning for the affected areas, estimating as much as 100 millimetres more rain could fall in the next two days.

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  • Emergency Declared In Southern Alberta After Heavy Flooding

    Houses damaged along the edge of Cougar Creek are shown June 20, 2013 in Canmore, Alta. Widespread flooding caused by torrential rains washed out bridges and roads prompting the evacuation of thousands.

  • Emergency Declared In Southern Alberta After Heavy Flooding

    Residents watch flooding along Cougar Creek June 20, 2013 in Canmore, Alta. Widespread flooding caused by torrential rains washed out bridges and roads prompting the evacuation of thousands.

  • Emergency Declared In Southern Alberta After Heavy Flooding

    Residents watch the flooding Cougar Creek as it takes out Eagle Terrace Road and nears the top of the Elk Run Blvd Bridge June 20, 2013 in Canmore, Alta. Widespread flooding caused by torrential rains washed out bridges and roads prompting the evacuation of thousands.

  • Emergency Declared In Southern Alberta After Heavy Flooding

    Houses damaged along the edge of Cougar Creek.

  • A lone truck sits submerged in the flood waters near downtown High River, Alta. on Thursday.

  • Homes along Cougar Creek in Canmore, Alta. barely hang on as the town struggles to deal with flooding Thursday.

  • A front end loader carries residents after they were rescued from the flood waters in High River, Alberta.

  • A kayaker paddles down a flooded street in High River, Alberta on Thursday.

  • Cars are submerged by the flood waters in High River, Alberta on Thursday.

  • Kevan Yaets swims after his cat Momo to safety as the flood waters sweep him downstream after submerging his truck in High River, Alberta on Thursday.

  • A woman is rescued from the flood waters in High River, Alta. on Thursday.

  • Kevan Yaets crawls out the back window of his pick up truck with his cat Momo as the flood waters sweep him downstream after submerging his truck in High River.

  • A helicopter carrying residents lands on a road in High River, Alta., Thursday.

  • Crystal Poirier, Roger Poirier

    Roger Poirier, holds his family's cat, Smartie, as his wife Crystal looks on after rescuing it from their flooded house in High River, Alta., Thursday.

  • Cars and homes are submerged in flood waters in High River.

  • Rescuers looks for stranded residents in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • A shot of the homes along Cougar Creek.

  • Semi truck sit idle to the Trans-Canada Highway in Canmore, Alta. on Thursday June 20, 2013. Calgary and most of southern Alberta are being hammered by rain that has washed-out roads and bridges, caused mudslides and closed major highways.

  • A flooded residence in High river, Alta. Heavy rains have caused flooding, closed roads, and forced evacuation in High River, Alta., Thursday, June 20, 2013.

  • A front end loader carries people to safety from the flood waters in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • Kevan Yaets swims after his cat Momo to safety as the flood waters sweep him downstream and submerge the cab in High River, Alberta on June 20, 2013 after the Highwood River overflowed its banks. Hundreds of people have been evacuated with volunteers and emergency crews helping to aid stranded residents.

  • A resident is comforted by rescuers as she clutches her dog after being retrieved from the flood waters in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • Bragg Creek Flood 2013 House Breaking

    A video of a house shattering against the bridge during the first day of the 2013 flood in Bragg Creek. I offer my sincerest condolences to those who lost th...

  • A lone truck sits submerged in the flood waters near downtown High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • Krystal Lelond of Black Diamond clutches her cat Pipi after being evacuated from her home after the Sheep River overflowed its banks.

  • An elderly woman is rescued from the flood waters in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • Debris and water pours across the Trans-Canada Highway as Canmore struggles with flooding.

  • A woman wades through the flood waters in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • Flooding in Black Diamond

  • This is the view of the bridge over the Highwood. Normally there is a couple metres clearance below it.

  • A kayaker paddles down a flooded street in High River, Alta. on June 20, 2013 after the Highwood River overflowed its banks.

  • One of several rock slides blocking #hwy40 in Kananaskis. No access to Kananaskis village.

  • Look at the flooding in #lethbridge !! This street has been shut down

  • Residents wade through flood waters after an evacuation order following heavy rains caused flooding, closed roads, and forced evacuation in High River.

  • A helicopter carrying evacuated residents lands on a road in High river, Alta. Heavy rains have caused flooding, closed roads, and forced evacuation in High River, Alta., Thursday, June 20, 2013.

  • The Bow river swells over its banks in downtown Calgary, Alta. Heavy rains have caused flooding, closed roads, and forced evacuation in Calgary, Alta., Thursday, June 20, 2013.

  • The Bow river swells over its banks in downtown Calgary, Alta. Heavy rains have caused flooding, closed roads, and forced evacuation in Calgary, Alta., Thursday, June 20, 2013.